Thermostat circuit



Jan. 1, 1935. R. J. PARSONS Er Al. 1,986,445

THERMOSTAT C IRCUIT Filed oct. s1, ll

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Patented Jan. l, 1935 UNITED STATES THERMOSTAT CIRCUIT Robert J. Parsons, Schenectady, and Ernest J. Heyman, Hampton Manor, N. Y., assignors to Consolidated Car-Heating Company, Inc., Albany, N. Y., a corporation of New York ApplicationOctober 31, 1931, Serial No. 572,360

9 Claims.` (Cl. 175-375) For a detailed description of the present form of or invention, reference may be had to the following specification and to the accompanying drawing forming a part thereof.

Our invention relates to means for enabling a thermostat to control an electric heater, it being understood that the thermostat action may be weak and delicate, while the effects of its action should be strong and forcible. We therefore provide means whereby the thermostat will merely close an electric c'vrcuit containing an electromagnetwhich can perform the work required, such, for instance, as the closure of an electricheater switch.

In the accompanying drawing, Figs. 1, 2, 3 and 4 show respectively four different forms of our fundamental device. l

Referring to Fig. 1, A represents a thermostat, herein indicated as of the bimetallic type. The contact arms a1 and a2 are both made of bimetallic strip and are suillciently flexible to move independently with respect to each other and with respect to the connecting cross piece z. These contacts engage` respectively with two fixed contacts b1 and b2. It will be understood that any other form of thermostatic device may be em` ployed to close one set of contacts on a rising temperature and to close a second set on the falling temperature. In Figs. 1, 2 and 3 the high temperature contact b2 is closed by a rising temperature and is lshown engaged by contact a2, while a falling temperature will cause the low temperature contact a1 to close on b1. A magnet C has its armature connected'to th/ermostat arm a1 and, when energized, acts to hold a1 against its stationary contact b1. As ai contacts with b1 there remains a momentary simultaneous contact of a2 with b2, with the result that the current passes from b1 to a1, a2 and b" to ground as illustrated in Figure 1, thereby bil-passing the magnet C and resulting in the deenergizing of' said magnet.

In series wlth magnet C is a relay D, which controls, at contacts d,d1, the electric heater R.. The 'contact of a1 with b1 momentarily short circuits both'C and D through rheostat S, which causes D to drop its armature and open the circuit of R.

Referring to Fig. 2, C vrepresents a holding i magnet arranged so that, when it is, energized,

it will hold contact arm a1 on contact with con tact b1, just as in Fig. 1. Fig. 1 shows the thermostat contacts in the high temperature position with an engaging b. In this position the heater control switch is open as the circuit of magnet C is broken at\,b1. As. the temperature' falls the contact arms 4 1 and cz will rise; a will break lwith bI and a1 will make 'withl b1, thus establishing a circuit for the heater controlswitch from trolley, through resistor S, through contacts bl and a1., through holding magnet coil C, through heater 'control= switch coil D, to ground. On the contrary, as the temperature rises, contact arms a1 and a2 will both tend to move downward. However, a1 will still be held up to its contact b1 as the holding coil C is now energized, with the result that the current will be caused to by-pass the magnet C, through b1, a1, a2, b2 and conductor e; whereupon said magnet C will be deenergized. Contact arm a2, on the contrary, moves downward, not being held by C, and ilnally makes 'contact with b2. This short circuits coils C and D, the armature of C lets go and a1, which is now under tension, drops down to the position shown in Fig. 1 and opens the circuit for coils C and D. Fig. 2 shows a circuit which gives results similar to those of Fig. 1 except that only coil C is short circuited.

Fig. 3 is similar to Fig. 2 except that coil D is located ahead of C in the circuit.

In Fig. 4 the contact arms a1 and a2 are shown in the low temperature position being the reverse of Figs. 1, 2 and 3 in that respect. Heater control switch coil D is now energized from trolley through resistor S, through coil D to ground. When the temperature rises both contact arms al and az move upward, a2 will break with b2 and al will make with b1. When a1 makes contact with b1 it places its holding coil C in parallel with the Iheater switch coil D, thus reducing the current through it to such a point that it drops out and opens the heater circuit. The temperature will .then fall and the contact arms al and azr will tend to ex downward, a2 moving toward the contact b2. However, a1 will be held in contact with bl by the holding coil C. As soon as a2 makes with b2, C will be short circuited and a1, which is now under tension, will break away from b1.

,Heretoforedevicesof this character were not adapted for use where vibration existed, such as on railway cars. By employing a holding coil, with means for energizing and deenerglzing it with slight temperature change, we not only provide means of preventing the contacts from being jarred open but also do not impair its sensitivity. Some devices employ la. holding coil, or

' permanent magnet, to hold the contacts from vibrating,'but as the magnets are commonly used, the operating range. that is, the temperature change required to operate the contacts, Ais too great for satisfactory results. As, for example, if

the magnet is holding a contact arm, there must stat consisting of two approximately parallel relatively movable temperature responsive portions electrically connected at one end, one of said members being so positioned that it moves into and out of the magnetic field of said magnet in response to a predetermined temperature change, means associated with the other portion of said thermostat for by-passing the holding magnet so as to eect release of the thermostat, and a contact-operating magnet controlled by said thermostat.

2. A thermostatic controller comprising means providing a circuit, a holding magnet, a contactoperating magnet, said magnets being in series in said circuit, an electro-conductive thermostat consisting oi two connected electro-conductive members arranged in series in said circuit, one o said members being provided with an electromagnetic portion so positioned that it will auto=.

matically move into the magnetic ileld of the holding magnet as the thermostat responds to a predetermined temperature change, said thermostat being constructed and arranged to control said contact-operating magnet, and means associated with said thermostat for tay-passing the holding magnet so as to eiiect release of said thermostat from magnetic attraction by said magnet.

3. A thermostaticcontroller comprising means providing a circuit, a holding magnet, a thermostat controlling saidcircuit, said thermostat consisting of apair of electrically connected relatively movable temperature responsive portions, one of which is provided with an armature so positioned that it will move into and out of the magnetic field of said holding magnet, a contact-operating magnet controlled by said thermostat, and

. means associated with the other portion of said thermostat for by-passing the holding magnet so as tol deenergize the same.

4. A thermostatic controller comprising means providing a circuit having two relatively spaced contacts, a holding magnet in said circuit, a thermostat consisting of two relatively movable elec- ..trlcally connected temperature responsive poi:-

tions, one of which is complemental to one of said contacts and the other complemental to the other contact, the rst mentioned movable portion being constructed and arranged to be responsive to magnetic attraction and so positioned that it will automatically move into the magnetic field of said magnet as the thermostat responds to a predetermined temperature change, means connected with the second contact to by-pass said holding magnet so as to deenergize the same, and a contact-operating magnet controlled by said thermostat.

5. A thermostatic controller comprising means providing a circuit having a pair of separated contacts, a holding magnet, a thermostat consisting of a pair of relatively movable electrically connected temperature responsive portions, one of which is complemental to one of said contacts and the other complemental to the other contact, the first mentioned thermostat portion having means constructed and arranged to act as an armature for said magnet ,and so positioned that it will move into and out of the magnetic field ofsaid magnet in response to a predetermined temperature change, a contactoperating magnet controlled by said thermostat and in series with the first mentioned magnet, and by-pass means connected to the second conmessage tact and with said circuit at a position between said magnets.

6. A thermostatic controller comprising means providing a circuit, a holding magnet, a U-shaped thermostat including two relatively movable temperature responsive portions electrically connected at one end, one of which is provided with an armature so positioned that it will automatically move into the magneticiield. ci said magnet as the thermostat responds to a predetermined temperature change, said portion being complemental to one of said contacts and the other portion of the thermostat being complemental to the other contact, a contact-operating magnet controlled by said thermostat and in series with the first magnet, and by-pass means connecting the second contact with the circuit between the magnets in a manner to by-pass and deenergize said holding magnet.

7. A thermostatic controller comprising means providing a circuit having a pair of spaced apart contacts, a holding magnet, a thermostat consisting of a pair of relatively movable electrically connected temperature responsive portions, one of which is complemental to one of said contacts and in series with said magnet, said last mentioned portion being constructed and arranged to be attracted by said magnet and to automatically move into the magnetic field as the thermostat responds to a predetermined ternperature change, the other portion of said thermostat being complemental to the other contact so as to by-pass said magnet, a contact-operating magnet controlled by said thermostat, said thermostat and said contacts being so constructed and arranged as to deenergize said magnet under lpredetermined temperature conditions.

8. A thermostatic controller comprising means providing a circuit having a pair of spaced apart contacts, a holding magnet, a thermostat consisting of two relatively movable electrically'connected temperature responsive portions, one oi which is complemental torrone of said contacts and in series with said magnet, said last mentioned portion being provided with an armature portion constructed and arranged to be attracted by said magnet and to automatically move into the magnetic field as the thermostat responds to a predetermined temperature change, the other portion of said thermostat being complemental to the other contact so as to by-pass said magnet, a contact-operating magnet controlled by said thermostat, said thermostat and said contacts being so constructed and arranged as to deenergize said magnet under predetermined temperature conditions.

9. A thermostatic controller comprising means providing a circuit,- a holding'magnet, a thermostat consisting of two approximately parallel electro-conductive members connected at one end and aranged in series with said magnet in said circuit, 'one of said members having an armature so positioned that it will automatically Amove into the magnetic field of the magnet as 

